The present invention relates in its generic type to a dispensing device for fluid substances. In particular it relates to a dispensing device which has a receiving element to receive fluid substances, having at least two containers which are fixedly connected to each other and have adjacent outlet orifices on the end face, a mixing nozzle which is connected to the receiving element by means of a mixing nozzle holder and is connected to the outlet orifices in a fluid-conducting manner, and a pressure-producing means for ejecting the fluid substances through the outlet orifices.
Dispensing devices such as these, which are used in particular for dental purposes, are known. Cartridges or double injection devices, for example, are used for mixing and for metered dispensing of dental multi-component materials and usually consist of two containers which are provided to receive two different substances. The containers are provided with outlet orifices on the end faces, which orifices are formed in such a way that mixing nozzles can be connected to them. The different components pressed out of the containers, for example, by stamping force meet in the mixing nozzle and exit this nozzle in the mixed state. After mixing, the mass hardens. This also applies to most of the residual quantity remaining in the mixing nozzle.
A device of this type is described in U.S. Pat. No. 4,767,026. In that case mixing nozzles are fixed in the manner of a bayonet connection to two holding elements by twisting over the outlet orifice of the containers. The disadvantage of this device is that the rotational movement of a mixing nozzle over the outlet orifices of the containers permits the components to contaminate each other and so permits hardening of the components in the outlet orifices and these outlet orifices can therefore become blocked.
An improved solution is a design in which the inlets of the mixing nozzles or of the outlet orifices of the containers are sufficiently separated from each other. This device is formed in such a way that the components only meet inside the mixing nozzle at a certain distance from the outlet orifices, which ensures that the hardening inside the nozzle remains restricted to a region sufficiently remote from the outlet orifices. In addition, this device permits a mixing nozzle, which is used to produce a mixture and which became unusable by reason of the hardening of its content, to be left as a quasi “temporary closure” of the outlet orifice on the containers until mixing is to take place using a newly fitted mixing nozzle.
A mixing nozzle of such a type is shown in U.S. Pat. No. 533,760. A bayonet closure is used but is rotatably held on the mixing nozzle so that after placing the nozzle on the outlet orifices of the containers only a holding ring is rotated which comes into positive-locking engagement in a pair of claws on the end face of the containers and therefore firmly holds the mixing nozzle. The ring is connected to the mixing nozzle in a complex manner and a relatively large number of rings are required, namely one per mixing nozzle.
This applies in a corresponding manner to another known arrangement (EP-A-730913) in which the bayonet coupling members are attached to the mixing nozzle housing in which an insert forming the inlet orifice of the mixing nozzle is contained so as to be rotatable relative to the housing.
A device in accordance with U.S. Pat. No. 4,753,536 consists of two containers fixedly connected to each other and containing the components, which containers have mutually adjacent outlet connection pieces on the end face. A mixing nozzle can be placed onto the outlet connection pieces and is to be secured in this position by a coupling device. The coupling device has a coupling plate which is supported by the outlet connection pieces and forms a guide extending transverse to the direction of the outlet connection pieces for two coupling slides. These can be displaced oppositely to each other on the guide into a closed position and support coupling strips which, in the closed position, each engage through 180° over a coupling flange of the mixing nozzle.
A device described in DE-100 38 882 A1 has a frame-like slide which can be displaced in linear guides of a coupling plate placed on the tube-like outlet connection piece of the containers, wherein the respective end stop indicates an opened or closed position. In this document reference is made to the advantage of a short force transfer path from the bearing to the clamping plane of the mixing nozzle holder.
All the systems mentioned above for fixing the mixing nozzles in or at outlet orifices which are sufficiently separated from each other have the disadvantage of an attachment element which has to be produced and mounted separately.
In contrast, it is the object of the present invention to provide an improved dispensing device which is simpler to produce and operate.